{"id":2219483,"url":"http://patchwork.ozlabs.org/api/covers/2219483/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/cover/20260403053748.78831-1-mohamed@unpredictable.fr/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260403053748.78831-1-mohamed@unpredictable.fr>","list_archive_url":null,"date":"2026-04-03T05:37:41","name":"[v4,0/7] whpx: i386: x2apic emulation for kernel-irqchip=off, feature probing","submitter":{"id":91318,"url":"http://patchwork.ozlabs.org/api/people/91318/?format=json","name":"Mohamed Mediouni","email":"mohamed@unpredictable.fr"},"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/cover/20260403053748.78831-1-mohamed@unpredictable.fr/mbox/","series":[{"id":498589,"url":"http://patchwork.ozlabs.org/api/series/498589/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=498589","date":"2026-04-03T05:37:41","name":"whpx: i386: x2apic emulation for kernel-irqchip=off, feature probing","version":4,"mbox":"http://patchwork.ozlabs.org/series/498589/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/covers/2219483/comments/","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=unpredictable.fr header.i=@unpredictable.fr\n header.a=rsa-sha256 header.s=sig1 header.b=PjltpKyZ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-Proofpoint-GUID":"Q74wh_MSVTdr0Vp0zwFJsF-KiiKmLcnJ","X-Authority-Info-Out":"v=2.4 cv=JJA2csKb c=1 sm=1 tr=0 ts=69cf5231\n cx=c_apl:c_pps:t_out a=bsP7O+dXZ5uKcj+dsLqiMw==:117\n a=bsP7O+dXZ5uKcj+dsLqiMw==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10\n a=VkNPw1HP01LnGYTKEx00:22 a=U-mDERgiERHxp3lFF3YA:9 a=QEXdDO2ut3YA:10","X-Proofpoint-ORIG-GUID":"Q74wh_MSVTdr0Vp0zwFJsF-KiiKmLcnJ","X-Proofpoint-Spam-Details-Enc":"AW1haW4tMjYwNDAzMDA0NyBTYWx0ZWRfX43FjF4OOhiT4\n 65zJxwKuglRHlxqrCk9lY0QriB/626R4AqG4S2GHIwWds8puZnQGzqe7ssItPsaZ6UgVzWx7Bky\n XknExmWdHSAX5liM/MQYr057O7wIqehqgN172+H9rIXPqAJk7WzplkcIGwoVKq3qlnSLktWNToT\n UxscqFmOyUy1dNQYr+OlB3oF2ILtRj7JARhCXlJjfgw44lbQMpElCaIwyqrlBIRMjviVI+IherN\n qGL+QkHpatp4md5TOkGGgNiINALNI7hbRiklDcXlzlKM0HHyLxE0FAEHmHwqWq8kVHif1uMm8vb\n 6VtUSSmJ/7/97z/ojenoUaNelnb7ISP9BgQxZqBtVwRVWqlv3R8LsxuuswQs+U=","X-Proofpoint-Virus-Version":"vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-04-03_01,2026-04-02_05,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=notspam policy=default score=0 mlxlogscore=583\n spamscore=0 suspectscore=0 lowpriorityscore=0\n clxscore=1030 mlxscore=0\n malwarescore=0 bulkscore=0 adultscore=0 phishscore=0 classifier=spam\n authscore=0 adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000\n definitions=main-2604030047","Received-SPF":"pass client-ip=57.103.87.73;\n envelope-from=mohamed@unpredictable.fr; helo=outbound.qs.icloud.com","X-Spam_score_int":"-27","X-Spam_score":"-2.8","X-Spam_bar":"--","X-Spam_report":"(-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"\"whpx: i386: disable TbFlushHypercalls for emulated LAPIC\" is a\nbugfix, and \"target/i386: emulate: include name of unhandled instruction\"\nis a debugging aid.\n\n\"whpx: i386: x2apic emulation\" makes things slightly better for Windows\n10 users. But I strongly recommend *not* relying on it when possible and\nusing kernel-irqchip=on instead. On Windows 10 however that's more murky\nbecause PIC interrupt injection is broken (interrupts don't wake the vCPU\nfrom HLT) in that case.\n\n\"whpx: i386: wire up feature probing\" is yet another commit adding a code path\nnot used on Windows 10. It'll tell the user today which CPU features they set\nare incompatible with the hardware but it does not sync that to the CPUID view\nthat the guest has.\n\nAnd then another commit to enable x2apic emulation by default even for\nkernel-irqchip=off + re-introducing provided by QEMU enlightenments in a more\nfunctional form to signal that the x2apic can be used. I'm not aware of the\nactual vmware freq leaf being used though.\n\n\"whpx: x2apic emulation for kernel-irqchip=off follow-up\" is rolled into this series.\n\n\"whpx: i386: reintroduce enlightenments for Windows 10\" is a bugfix to make\nx2APIC work as intended on Windows 10 without emulating an IOMMU.\n\nAnd then at the end but dependent on this series, CPUID intercepts finally...\nHowever that's only supported starting from Windows 11/Server 2022.\n\nSome performance (or lack thereof...) numbers:\n\nOn a Ryzen 7 8700GE with a Windows 10 VM running with KVM in nested virt, with\nkernel-irqchip=off for the virt Alpine Linux x86_64 ISO (3.23.3) with -smp cores=2,\nboot times as reported through dmesg:\n\n- QEMU 10.2: 83 seconds\n- QEMU 10.2 with a single core: 18.1 seconds\n- as of this series, x2apic forced off: 29 seconds\n- as of this series, out of the box: 18 seconds\n- and with 1 core instead of two: 12.6 seconds\n\nAnd with this series on a Windows 11 VM on the same hardware:\n- kernel-irqchip=on: 6.5 seconds\n- kernel-irqchip=on, x2apic forced off: 7.6 seconds\n- kernel-irqchip=off: 8.3 seconds\n- hyperv=off,kernel-irqchip=off: 7.6 seconds... which is faster,\nso the absence of enlightenment support on Windows 10 doesn't explain things...\n\nWith kernel-irqchip=on on Windows 10, when booting with SeaBIOS, it gets stuck in\nsyslinux due to PIC interrupt injection being broken there. That can be counted\nas an infinite boot time (?).\n\ncheckpatch false positives:\n\nERROR: spaces required around that '*' (ctx:WxV)\n+ UINT32 Ecx, WHV_CPUID_OUTPUT *CpuidOutput))\n\nNot a multiplication but a pointer reference.\n\nERROR: space prohibited after that '&' (ctx:ExW)\n+ & CPUID_7_0_EDX_CET_IBT) {\n ^\n\nERROR: space prohibited after that '&' (ctx:ExW)\n+ & CPUID_7_0_ECX_CET_SHSTK) {\n ^\n\nBecause it's multiline.\n\nChanges in v4:\n\n- Ugh for a revision sent quickly, unbreaking the arm64 build...\n- and making checkpatch happier to some extent\n\nChanges in v3:\n\n- Fixing CPUID intercepts so that QEMU CPU models work fine now, instead\nof the partial intercept that was present in QEMU 10.2\n- cleanups\n\nChanges in v2:\n\n- GCC warned when a variable name was re-used within a different (but overlapping)\nscope in the same function. It also warned with a -Werror=maybe-uninitialized for\nthe MSR write case. Address those\n- make the in-KVM enlightenments path available on Windows 11 too when -M hyperv=off.\n\nMohamed Mediouni (7):\n target/i386: emulate: include name of unhandled instruction\n whpx: i386: x2apic emulation\n whpx: i386: wire up feature probing\n whpx: i386: disable TbFlushHypercalls for emulated LAPIC\n whpx: i386: enable x2apic by default for user-mode LAPIC\n whpx: i386: reintroduce enlightenments for Windows 10\n whpx: i386: introduce proper cpuid support\n\n accel/whpx/whpx-common.c | 2 +\n include/system/whpx-internal.h | 10 ++\n target/arm/whpx/whpx-all.c | 1 +\n target/i386/cpu.c | 25 +++\n target/i386/emulate/x86_emu.c | 4 +-\n target/i386/whpx/whpx-all.c | 295 ++++++++++++++++++++++++++++++++-\n target/i386/whpx/whpx-i386.h | 4 +\n 7 files changed, 331 insertions(+), 10 deletions(-)\n create mode 100644 target/i386/whpx/whpx-i386.h"}